Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 May 2021 | 13(6): 18544–18550
ISSN 0974-7907 (Online) | ISSN 0974-7893
(Print)
https://doi.org/10.11609/jott.5412.13.6.18544-18550
#5412 | Received 16 December 2019 | Final
received 09 March 2021 | Finally accepted 27 March 2021
Conservation breeding
of Northern River Terrapin Batagur baska (Gray, 1830) in Sundarban Tiger Reserve, India
Nilanjan Mallick 1, Shailendra Singh 2,
Dibyadeep Chatterjee 3 & Souritra
Sharma4
1,3,4 Sundarban Tiger Reserve, Canning Town, South 24 Parganas, West Bengal 743329,
India.
2 Turtle Survival Alliance, India- D1/317,
Sector F, Jankipurum, Lucknow, Uttar Pradesh 226021,
India.
1 nmallick66@yahoo.co.in,
2 shai@turtlesurvival.org (corresponding author), 3 dibyadeep2190@gmail.com,
4 souritra.shrm@gmail.com
Editor: L.A.K.
Singh, Bhubaneswar, Odisha, India. Date
of publication: 26 May 2021 (online & print)
Citation: Mallick, N., S. Singh, D.
Chatterjee & S. Sharma (2021). Conservation
breeding of Northern River Terrapin Batagur
baska (Gray, 1830) in Sundarban Tiger Reserve, India. Journal of Threatened Taxa 13(6): 18544–18550. https://doi.org/10.11609/jott.5412.13.6.18544-18550
Copyright: © Mallick et al. 2021. Creative Commons Attribution
4.0 International License. JoTT allows unrestricted use, reproduction, and
distribution of this article in any medium by providing adequate credit to the
author(s) and the source of publication.
Funding: West Bengal
Forest Department; West Bengal State Zoo Authority; IUCN
Save our Species (SOS) 2012A-031 (2014); Ocean Park Conservation Fund, Hong Kong- OPCFHK_RB02_1516 (2015–2016);
People Trust for Endangered
Species- (2015-2016); Auckland Zoo (2014–2015); Alan and
Patricia Koval Foundation.
Competing interests: The authors
declare no competing interests.
Author details: Mr. Nilanjan
Mallick is current Additional Principal Chief Conservator of Forests and
Chief Conservator of Forest, Finance, West Bengal. He is an officer of 1996
batch of Indian Forest Service (West Bengal Cadre). He has two decades of
experience working in Forest and Wildlife Maanagement
and had worked in Sunderban Tiger Reserve for 10
years. Dr.
Shailendra Singh spearheads the India Program of Turtle Survival
Alliance. He is Regional Vice Chair of
IUCN’s Tortoise and Freshwater Turtle Specialist Group - South Asia.
With more than 18 years of experience, he supervises six long-term chelonians
conservation projects in five Turtle Priority Areas (TPAs) in the country. Mr. Dibyadeep Chatterjee, presently working as project
associate at Wildlife Institute of India (WII) in the project entitled
“Population management of species involved in human-wildlife conflict”. He is
also a PhD affiliate with the faculty of wildlife sciences at WII. Mr. Souritra Sharma, currently employed as project
fellow under Wildlife Institute of India, Dehradun, Uttarakhand, for the
project “Population management of species involved in human-wildlife conflict”.
Author contributions:
Design and conception of the study: Nilanjan Mallick
and Shailendra Singh. Field setup design
and structure: Nilanjan Mallick and Shailendra
Singh. Data collection and analysis:
Shailendra Singh, Dibyadeep Chatterjee, and Souritra Sharma.
Wrote the paper: Shailendra Singh, Dibyadeep
Chatterjee, and Souritra Sharma.
Ethical Standards: All the required work has been
done in accordance with the ethical standards and under the permit from the
principal chief conservator of forests, wildlife 448/41/4R-1(pt-VIII) 10 dated 15 th February,
2010.
Acknowledgements: We are thankful to Sri Ravi Kant
Sinha, principal chief conservator of forests and head of forest force, West
Bengal for constant encouragement and permit 448/41/4R-1(pt-VIII)
10 dated 15 February, 2010. We sincerely
thank Sri. V.K Yadav PCCF(WL - West Bengal) and chief wildlife warden for his
guidance and support. We would also like to thank Sri Piar
Chand, additional principal chief conservator of forest (APCCF) and director, Sundarban Biosphere Reserve for providing support and
facilities towards setting up of breeding facility. We would like to thank Mr. Soumitra Dasgupta, former field director, STR. We also thank the veterinary officer of Sundarban Tiger Reserve, Dr. Sankar
Sekhar Biswas, for helping in monitoring the health of turtles during the
initial stages of the project. SS thanks
various organisations such as IUCN Save our Species
(SOS); Ocean Park Conservation Fund, Hong Kong; People Trust for Endangered
Species, Auckland Zoo and Alan and Patricia Koval
Foundation for funding various scientific component of the project between
2012–2019. Madras Crocodile Bank
Trust/Centre for Herpetology is thanked for providing technical inputs. Mr Rick Hudson, Mr Andrew Walde, Dr Gerald Kuchling, Mr Lonnie McCaskill are thanked for suggestions and
inputs. Dr Niladri Dasgupta, Dr Disha
Sharma, Dr. Preeti Goswami,
Mr. Shashwat Sirsi, Mr Saurav Gawan, Mr Sayantan Ghosh are thanked for
assistance in field and data collection.
West Bengal State Zoo Authority provided additional funding for building
assurance colonies. Various officers and
staff members of Sunderban Tiger Reserve are thanked
for logistics helps.
Abstract: The
population of Northern River Terrapin Batagur
baska is ‘Critically Endangered’ and threatened
with extinction. In India, the species
was once known to occur in the mangroves of West Bengal and Odisha. The sub-population in Odisha is suspected to
have been wiped out. The Sundarban Tiger Reserve and the Turtle Survival Alliance
launched a modest conservation breeding program in 2012 to recover the species
using a small number of adults as founders.
Gravid adult females are kept in a dedicated breeding enclosure with
minimal disturbance, eggs are incubated outdoor on an artificial nesting beach,
and hatchlings are raised to develop assurance colonies for purposes of
reintroduction in future. Currently, the
project holds 12 adults and over 350 juveniles of various size classes. Three additional assurance colonies were
developed for 70 sub-adults from 2012–13 batches, using rain-fed ponds within
STR.
Keywords: Critically Endangered, Four-toed Terrapin, Freshwater
turtles, Geomydidae, river turtle, Testudines.
INTRODUCTION
Distribution and status of Batagur baska
The Indian subcontinent has one
of the richest assemblages of chelonians in the world, with 29 freshwater
turtles (Mital et. al 2019) and tortoises, of which
all the members of the genus Batagur are
seriously threatened. Batagur baska (Gray, 1830), commonly known as the Northern River Terrapin
or Four-toed Terrapin, is a giant river turtle belonging to the family Geoemydidae within the order Testudines. B. baska is
listed as ‘Critically Endangered’ in the IUCN Red List (Praschag
& Singh 2019), and is recognised as one of the top 25 endangered turtle
species in world (Turtle Conservation Coalitions 2018). The species is also listed in the Appendix–I
of the CITES.
Formerly believed to have been a
single species ranging across the entire southeastern
Asian region, B. baska is actually one of two
genetically distinct species (Praschag et al.,
2007). The populations of river terrapins
of Thailand, Malaysia, and Indonesia are now listed as the Southern River
Terrapin Batagur affinis,
while the northern species from India to Myanmar has retained the name B. baska (Praschag et al. 2008b,
2009; Weissenbacher et al. 2015; Praschag
& Singh 2019).
Historically, B. baska was found in Odisha and the Hooghly River mouth,
West Bengal (Blyth in. Gunther, 1864) in India, through to Bangladesh and
Myanmar (lower Ayayarwady, Sittanug,
and Thanlwin), and possibly as far south as the
Andaman Sea side of Thailand at the Kra River. Batagur was
distributed in all the coastal districts of Odisha (Orissa), particularly the
deltaic regions of Mahanadi, Brahmani, Baitarani, Dhamra and Subarnarekha, but Mishra, et al. (1996) believed
it might have got extinct. During the
last recorded river survey in West Bengal and Odisha, while no evidence of a
single population of B. baska was found from
well-known habitats of this species in Odisha (Praschag
et. al 2008a), nesting females were confirmed to be surviving in the Indian
Sundarbans of West Bengal. Furthermore,
of the last 10 nesting females informed by Bhupathy
(1995), Prachag’s survey only reported one of these
females to be nesting on the beaches of Mechhua
Island (Praschag 2008a; Moll et al. 2009). B. baska is
now primarily limited to the Sundarbans area of India and Bangladesh, with the
exception of three females in two different temple ponds in Myanmar (Praschag & Singh 2019).
Though an aquatic species, it
also uses sandy nesting beaches along the sea, frequenting the tidal zones of
estuaries, large rivers and mangroves (Asian Turtle Trade Working Group,
2000). Nests are often subject to
predation by Water Monitor Lizards Varanus salvator or Rhesus Macaques Macaca
mulatta.
Singh et al. (2014) also found spoors and signs of severe digging by
Wild Boar Sus scrofa, possibly in search of
turtle nests in Mechhua and other sea facing sandy
beaches in the Indian Sundarbans. Also,
intense exploitation of the eggs and adults pertaining to illegal wildlife
trade is considered to be the key driver of massive decline of Batagur population.
With an estimate of less than 40
animals in India (Praschag & Singh 2019) the only
plausible solution to recover this species is conservation breeding followed by
supplementation in the wild. Sundarban is the only known abode of B. baska in India, and some successful hatching of the
species has occurred at the Madras Crocodile Bank Trust (Whitaker, in Singh
2014). West Bengal Forest Department,
with the help of the Turtle Survival Alliance (TSA) has been attempting to
recover Batagur baska
species since 2008. In August of the
same year, 12 adults were captured and examined by researchers with assistance
from local fishermen in the Sajnekhali range of the
Indian Sundarbans (Singh & Saha 2008), which led
to re-instating the breeding programme in the STR after a gap of about 20
years. The objective in the present note
is to put in record the information about the efforts made for conservation of B.
baska in Sundarbans, West Bengal in India.
CONSERVATION OF BATAGUR IN
SUNDARBANS
The Batagur
population
The local Bengali name for Batagur baska is ‘pore katha’ for male, and ‘sundi’ or ‘balli katha’ for female (Das
1985). Since the 1980’s ex situ
conservation program for the Olive Ridley Turtle Lepidochely
solivacea was operational in STR, when eggs of
the species were collected from wild nests and incubated in controlled
environment at Sajnekhali. Subsequently, the hatchlings were released in
the sea. During the nesting season of
1983, amongst the Olive Ridley hatchlings there were nine hatchlings of some
other species, which were later identified as B. baska
(Ghosh & Mandal 1990).
In 1988, three clutches of eggs
of Batagur were translocated from Mechhua to Parkhiralaya (Ghosh
& Mandal 1990), followed by 24 more nests in 1988 to 1991 (Ghosh &
Mandal 1990; Moll et al. 2009).
Subsequently, the West Bengal Forest Department began captive breeding
followed by hatch-and-release program for B. baska
in the Sajnekhali Range Station within STR, where
less than 50% of the eggs hatched after artificial incubation (Bhupathy et al 1995).
In the late 1990s, the hatch-and-release program was abandoned and the
remaining captives were subsequently released in nature (Moll et al. 2009).
Observations recorded from Sajnekhali or its surroundings from 2008 onwards included
detection of turtles, their relocations, occasional escapes, nesting,
collection of eggs, incubation of eggs under supervision, hatching of young
turtles, and housing of turtles in the available facility (Singh & Saha 2008; Pandit 2013; Singh 2013).
Housing facilities for Batagur in Sajnekhali, Sundarbans
1. The breeding enclosure, built
in 2018 is of length (L) x width (W) x depth (D) of 16.40m × 14.50m x 9m,
provided with artificial sand bank (7m × 5.8m) for nesting and two basking
platform of 3m ×3m size (Figure 3 iii).
The enclosure is covered with agro-net, topped
with nylon net fencing to avoid predators as well as excessive sun. Females Batagurs of
2012 constituted the founder colony for nesting (Table 1).
2. The temporary nesting
enclosure/ yearling pool is a make-shift ‘8’-shaped enclosure, measuring LxWxD 20.6m × 5.5-9.40m x 3.5m (Figure 3 i), with nylon net fencing on all sides. During the nesting season a few gravid
females are shifted here for nesting.
The turtles of 2016 batch are also retained here.
3. The retention pond is an
earthen pond of 39.70m x 35.31m size x 3.65m depth (Figure 3 ii). It is the main holding facility in
Sundarbans. It holds Batagurs
of the founder colony and turtles of batch 2013 and 2014.
4. The old nursery is 7.55m x
3.5m x 50cm (Figure 3; no. v) and the new nursery is 9m x 2.5m x 70cm (Figure 3
iv) with two hatchling ponds. This
facility is enclosed from all sides for thermoregulation and to avoid
predation. After the incubation period of
about 60 to 66 days the hatchlings are collected and shifted to this enclosure. After the transfer, hatchlings are retained
here for the next six months.
Assurance facilities at Chamta, Jhingekhali, and Netidhopani and their usage
As the Sundarbans is prone to
storm, it became essential to set up assurance colonies in order to avoid total
wipe-outs, as was feared in 2009, when tropical storm Aila
hit the Sundarbans, when one adult male escaped due to overflow of water from
the original earthen pond. Aiming for
circumventing overcrowding, natural disaster and also as a precautionary
measure in case of an outbreak of any contagious disease, the assurance colony
ponds were set up at three islands namely Chamta, Jhingekhali, and Netidhopani,
near forest department head-quarters, besides Sajnekhali,
within STR.
These facilities are rain-fed
earthen ponds, the embankments of which are fenced to ward off predatory
animals such as V. salvator. These ponds measure, Netidhopani:
40m x 7m x 2m depth (Figure 4, i); Chamta: 30m x 32m x 3m depth (Figure 4, ii), and Jhingekhali: 25m x 16m x 2m (Figure 4, iii).
Turtles from
the 2012–2014 batches were transferred to these ponds, and now they hold 70
individuals of B.baska juveniles and
subadults. Other shifting were 20
individuals (13 female, 7 male) in March 2017, 34 in September 2017 to the Netidhopani sweet water pond and 16 individuals (13 female,
3 male) in November 2017 to the Jhingekhali sweet
water pond.
The characteristics of water in
captivity
The pH of Sajnekhali
rain-fed pond is 7.68 and the salinity is 0.86 PSU, assumed to be conducive for
long term retention of the species.
Thus, basic physiochemical parameters of the three assurance colony
ponds were tested (Table 2) to keep the level of salinity and pH adjusted in
reference to the Sajnekhali; however, the result
depicted a higher measure of salinity in the pond located at Jhingekhali compared to other ponds (Figure 2). Therefore, all three ponds were conditioned
by adding fresh river water to keep the salinity under 10 part per thousand
(ppt), and to correct the alkalinity and pH of the water matching with the
specifications of the Sajnekhali Pond.
Hatching of the eggs and tending
of the hatchlings and transfer to yearling pool
Gravid females after examination
for calcified eggs in late February or early March are shifted to the breeding
pond for nesting. By the third week of
March the females lay their eggs, which are determined with emergence, nesting
tracks and camouflaging of nest cavity by the females. During 2015 and 2018, no eggs hatched, the
reason for which is non-conclusive
The eggs laid by the females are
kept on an artificial sand beach and a temperature of about 30–32 °C is
maintained by mimicking the reported nest depth and providing additional shade
in breeding enclosure. Temperature and
humidity of the nest were continuously tracked using temperature data
loggers. After an incubation period of
about 60–66 days the eggs hatch during end of May. The hatchlings are then collected and shifted
to the nursery (hatchling enclosure).
The artificial nesting bed is monitored for about five days from the
time of emergence of the first hatchling.
Generally, all the eggs hatch in about two days’ time. The hatchlings are transferred to the nursery
pens, and are fed with aquatic plants and vegetables for the next six months. After one year, when the hatchlings weigh
approximately 250g, they are transferred to the yearling ponds, which offer a
larger area and deeper water.
In July 2018, five juveniles from
the 2017 batch showed symptoms like sloughing off part of the face, including
the mouth region, nose and eye. Two of
these individuals succumbed to death during treatment. Four swab samples examined at the Institute
of Animal Health and Veterinary Biologicals, Kolkata tested negative for
bacteriological infections, but tested positive for the Herpesvirus
glycoprotein B. All the infected
individuals died in a few weeks’ time and carcasses were carefully
disposed. The remaining non-infected
individuals were taken out of the adult pool for necessary treatment and
observation and later quarantined as a precaution.
Currently, there is no data on
survival and dispersal of Batagur in Sundarban. The
soft-release enclosure was blown away in a storm in February 2016 and all 10
telemetered animals escaped.
DISCUSSION
Batagur baska is not known to have any viable
wild population in the last 20 years, which possibly suggest that the species
has become functionally extinct from much of its range. Sundarbans Tiger Reserve has carried out
assisted breeding program since 2012, and has 359 individuals in captivity
today, making it the largest holding of Batagur
anywhere. Batagur
recovery initiative is also carried out in Bangladesh in association with
Vienna Zoo and TSA. The present account
shows that the entire process in Sundarbans has been a learning experience.
Table 1. Year-wise captive stock
of Batagur baska
in Sundarbans
|
Stock |
Numbers |
Source |
Place of housing |
Usage |
|
2008 |
12 founders |
Reported from Sajnekhali pond |
Retention pond at Sajnekhali |
Founder colony |
|
2012 |
33 hatchlings |
founder colony of 12
individuals |
Retention pond at Sajnekhali |
Development of assurance colony
and wild supplementation |
|
2013 |
55 hatchlings |
Founder colony of 12
individuals |
Retention pond at Sanjekhali |
Development of assurance colony
and wild supplementation |
|
2014 |
57 hatchlings |
Founder colony of 12
individuals |
Retention pond at Sanjekhali |
Development of a ssurance colony and wild supplementation |
|
2016 |
96 hatchlings |
Founder colony of 12
individuals |
Temporary breeding cum holding
facility in Sajnekhali |
Development of assurance
colony, survival dispersal study |
|
2017 |
74 hatchlings in 2017, |
Founder colony of 12
individuals |
Old Nursery in Sajnekhali |
Development of assurance colony
and wild supplementation |
|
2019 |
50 hatchlings |
Founder colony of 12
individuals |
New Nursery in Sajnekhali |
Development of assurance colony
and wild supplementation |
Table 2. Results of
water tests done on three assurance colonies by an external laboratory
recognised by the West Bengal Pollution Control Board.
|
Parameters |
Assurance colonies |
||
|
|
Chamta |
Netidhopani |
Jhingekhali |
|
pH Value (at 25"C) (APHA 22ND'Edition4. 500-H -B) |
6.02 |
6.88 |
6.97 |
|
Total Alkalinity (as CaCO3),
mg/ml (IS: 3025(Part-23)-I986) |
<5.0 |
77.2 |
198 |
|
Nitrate (as NO3), mg/ml (APHA 22ND Edition,4 500N Or'E) |
< 0.5 |
< 0.5 |
< 0.5 |
|
Salinity (PSU) (Electrical Conductivity
Method) |
0.09 |
< 0.5 |
1.78 |
For
figures & images - - click here
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